* scd/ccid-reader.c (scan_usb_device): Only for scan mode, so, rename
from scan_or_find_usb_device.
(scan_devices): Likewise.  Remove support of special transport types.
(ccid_get_reader_list): Simplify.
(abort_cmd): Fix error return.
(send_escape_cmd): Fix for RESULTLEN == NULL.
(ccid_transceive_secure): Remove unnecessary var updates.